Modelling the influence of thermal state and sliding on the dynamics of Grenzgletscher, Swiss Alps

Alpine glaciers provide an accessible window into the dynamics of Antarctic ice streams, providing key insights into the processes controlling ice flow. Grenzgletscher, a polythermal glacier in the Swiss Alps, has cold-bedded ice in the accumulation zone and temperate-bedded ice downstream. The location of the transition between these basal regimes remains poorly constrained. We build a full-Stokes ice flow model with Elmer/Ice to reproduce observed surface velocities under varying basal conditions. Three scenarios are tested: (1) a frozen bed (no slip); (2) sliding with spatially variable basal friction; and (3) inclusion of borehole-derived temperature profiles to evaluate the influence of thermal structure on flow. The study provides constraints for geophysical investigations where surface velocities are not matched and informs a borehole campaign planned for next summer targeting the cold-temperate transition. These simulations aim to clarify how basal thermal state and sliding jointly shape glacier dynamics.